Tray-like dental bleaching devices having a barrier layer and a substantially solid bleaching composition

ABSTRACT

Dental bleaching devices in the shape of a dental tray or tray-like form include an outer barrier layer and an inner bleaching layer. The bleaching layer comprises a substantially solid dental bleaching composition that has increased adhesiveness to teeth when moistened with saliva or water. The shape of the dental bleaching device facilitates placement of the device over a person&#39;s teeth with substantially less manipulation compared to the use of initially flat bleaching strips. The substantially solid dental bleaching composition becomes more adhesive when moistened with saliva or water, yet remains intact and coherent after the dental bleaching device is placed over a person&#39;s teeth during bleaching. The result is that the moistened dental bleaching composition is able to reliably adhere the dental bleaching device against a user&#39;s teeth during a bleaching procedure. However, because a substantial portion of the dental bleaching composition remains solid or semi-solid during bleaching, the bleaching composition maintains a substantial portion of its adhesive properties and internal cohesive strength.

BACKGROUND OF THE INVENTION

[0001] 1. The Field of the Invention

[0002] The present invention is in the field of dental bleaching devicesused to bleach a person's teeth. More particularly, the inventionrelates to dental trays and tray-like barriers loaded with asubstantially solid dental bleaching composition that becomes adhesivewhen moistened (e.g., by a saliva on user's teeth).

[0003] 2. The Relevant Technology

[0004] Virtually all people desire white or whiter teeth. To achievethis goal, people either have veneers placed over their teeth or havetheir teeth chemically bleached. In the past, patients who desired tohave their teeth bleached had to submit to conventional in-officebleaching techniques. The process generally involves: (1) making analginate impression of the patient's teeth; (2) making a stone cast ormodel of the impression; (3) vacuum forming a dental tray from themodel, usually from a heated sheet of thin ethyl vinyl acetate (EVA)material, and (4) trimming to exclude gingival coverage. This methodresults in a tray that is soft and flexible, that is customized to veryaccurately fit over the patient's teeth, and that is therefore verycomfortable to wear. However, the process for making a customized trayis time consuming, often taking days or weeks before the customized trayis available to the patient, and the resulting tray can be expensive.

[0005] Because of the time and cost associated with customized trays,less time consuming and costly alternatives have been developed.Contrary to marketing campaigns, however, many alternatives havesubstantial disadvantages, primarily in terms of their effectiveness (orineffectiveness) in actually bleaching teeth. They also have their ownunique issues relating to ease of use, comfort and poor taste (bleachingcompositions are, after all, placed directly into a person's mouth).

[0006] One alternative to customized dental trays are non-customizedtrays that approximate the shapes and sizes of a variety of users'dental arches. While non-customized dental trays can be used without theneed for a professional customization procedure by a dentist, such traystend to be more bulky and less comfortable than custom-fitted trays.Dental Trays that can be self-customized (e.g., so-called “boil andbite” trays) are somewhat more comfortable and better-fitting comparedto non-custom trays but less comfortable than trays that are customizedby a dentist.

[0007] Another alternative tooth bleaching method involves painting ableaching composition directly onto the surfaces of a person's teeth tobe bleached. An advantage of this procedure is that it eliminates theneed to obtain a customized tray, or even a non-custom tray. The maindisadvantage, however, is that the bleaching composition remainsdirectly exposed to the person's saliva and disruptive forces andmovements normally found within a person's mouth. The result is that asignificant portion of the bleaching composition does not remain on thetooth where bleaching is desired. Instead, some or all of thecomposition can dissolve away into the person's saliva and/or betransferred to adjacent oral tissues. Because paint-on dental bleachingcompositions, like all dental bleaching compositions, containperoxide-based bleaching agents, irritation to soft oral tissues withinthe user's mouth and throat is a potential problem when using suchcompositions.

[0008] Yet another alternative tooth bleaching method involves placing aflexible bleaching strip over a user's tooth surfaces. Bleaching stripstypically comprise a flexible plastic strip coated with a moist dentalbleaching gel on the side of the strip facing the user's teeth. Toinstall the bleaching strip, a portion of the bleaching strip is firstplaced over the front surfaces of the user's teeth, followed by foldingthe remainder of the strip around the occlusal edges of the teeth andback against a portion of the lingual surfaces. Like paint-on bleachingcompositions, this procedure does not require the user to obtain acustomized tray, or even a non-custom tray, into which a bleachingcomposition must be placed by the user prior to use. An advantage ofbleaching strips over paint-on bleaching compositions is that bleachingstrips include a barrier that, at least in theory, protects the dentalbleaching gel from diffusing into the user's mouth.

[0009] In reality, however, because of the generally poor adhesion ofbleaching strips to the user's teeth, coupled with their generallyflimsy nature, it is often difficult for the user to maintain thebleaching strips in their proper position. Bleaching strips are prone toslip off the teeth through even minimal movement of the user's mouth,jaw or tongue. Indeed, it is recommended that the user not eat, drink,smoke or sleep while wearing the bleaching strip. In practice, it isdifficult to talk while maintaining the bleaching strips properlyoriented over the teeth to be bleached.

[0010] Even if a user successfully maintains the bleaching strip in itsproper position during the entire bleaching event, the flowablebleaching gel can diffuse into the person's saliva, potentially causinga poor taste in the user's mouth and possibly discomfort to soft oraland throat tissues. The tendency of the bleaching gel to diffuse intothe user's mouth can be accelerated through even minimal shifts of thebleaching strip over the user's teeth, with each shift potentiallyexposing a new portion of the bleaching gel that remains adhered to thenewly exposed surface of the user's teeth. In some cases, the bleachingstrip can become so dislodged or mangled that it must be removed by theuser and replaced with a fresh bleaching strip to complete therecommended bleaching time. This multiplies the cost and hassle of thebleaching strip method.

[0011] In practical terms, the use of bleaching strips can greatlyinhibit even the simplest of activities that involve movement of theuser's mouth or tongue, such as talking, smiling, making other facialexpressions, or even swallowing (which normally occurs subconsciouslythroughout the day). Indeed, the time when a person's mouth and tongueare prone to move the least is at night while the person is sleeping.Unfortunately, it is recommended that bleaching strips not be used whilesleeping, presumably to prevent accidental choking on an inadvertentlydislodged bleaching strip. This only confirms the tendency of suchbleaching strips to easily dislodge from a user's teeth.

[0012] Ultimately, the main impediment to successful bleaching is thefailure of users to complete the prescribed bleaching regimen. If thebleaching apparatus is difficult to use, requires numerous repetitionsto achieve observable results, or is simply uncomfortable or a hassle towear, the user may simply give up and abort the bleaching processaltogether. Thus, even if significant dental bleaching is possible usinga particular bleaching product, it is less likely to occur where theinadequacies of the bleaching apparatus or method causes users to becomediscouraged before desired results are attained.

[0013] In view of the foregoing, there is an ongoing need for improvedbleaching apparatus and methods that are simple and easy to use, thatmore reliably remain in position over the user's teeth, and that resultin less diffusion of bleaching composition into a user's oral cavity.Such improvements would be expected to improve or encourage complianceby the user.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS

[0014] The present invention generally relates to improved dentalbleaching devices used to bleach a person's teeth. Briefly summarized,the inventive dental bleaching devices include a moisture-resistantbarrier layer, such as a dental tray or tray-like barrier, and ableaching layer comprising a substantially solid dental bleachingcomposition that becomes more adhesive to teeth when moistened (e.g., bysaliva or water). When placed over a person's teeth, the dentalbleaching composition reliably adheres to the teeth, maintaining contactbetween the teeth to be bleached and a bleaching agent within thebleaching composition. The barrier layer protects the dental bleachingcomposition from diffusing away from the person's teeth as a result ofambient saliva or moisture found within the person's mouth.

[0015] According to one embodiment of the invention, the barrier layercomprises a thin, flexible membrane formed from a moisture-resistantpolymer material. Nevertheless, it is within the scope of the inventionto provide barrier layers having any desired thickness or rigidity. In apreferred embodiment, the barrier layer comprises a thin layer of apolyolefin or similar moisture-resistant material. The barrier layer maycomprise a conventional dental tray, examples of which include bothcustomized and non-custom dental trays. The barrier layer may be assimple as a layer of a moisture resistant material that is sprayed orpainted on, applied by dipping, or otherwise applied to an existingbleaching layer comprising a substantially solid dental bleachingcomposition (e.g., one that is in the form of a dental tray or thatotherwise has a desired shape).

[0016] In one embodiment, the bleaching layer comprises a substantiallysolid, coherent dental bleaching composition, as opposed to a liquid,gel, or dry particulate or powdery bleaching composition. As such, thebleaching layer comprises one or more coherent regions or masses of adental bleaching composition that do not readily run or flow. Providinga substantially solid and coherent bleaching layer better maintains thebleaching composition between the barrier layer and the teeth beingbleached and helps prevent diffusion into the surrounding oral cavity.This, in turn, promotes better tooth whitening and reduces irritation tosurrounding oral tissues and/or at least some of the bad taste normallyassociated with dental bleaching.

[0017] The substantially solid dental bleaching compositions accordingto the invention include at least one dental bleaching agent and atleast one tooth adhesion agent. Preferred dental bleaching agentsinclude solid complexes of hydrogen peroxide. Non-limiting examples ofdental bleaching agents that are a solid complex of hydrogen peroxideare carbamide peroxide and sodium perborate, although it is within thescope of the invention to use other dental bleaching agents known in theart.

[0018] In one embodiment, the tooth adhesion agent advantageouslyremains substantially non-adhesive when the dental bleaching compositionis in a dry or substantially solid condition but becomes adhesive toteeth when the dental bleaching composition is moistened with, e.g.,water or saliva. A non-limiting example of a suitable tooth adhesionagent is polyvinyl pyrrolidone (PVP), although it is within the scope ofthe invention to use other tooth adhesion agents known in the art.

[0019] The dental bleaching composition may include other components asdesired to yield a final composition having desired properties. Examplesof other components include, but are not limited to, plasticizers andhumectants (e.g., glycerin, sorbitol, and polyethylene glycol), volatilesolvents (e.g., water and alcohols), stabilizing agents (e.g., EDTA),neutralizing agents, thickening agents (e.g., fumed silica),desensitizing agents (e.g., potassium nitrate), remineralizing agents(e.g., sodium fluoride or other fluoride salts), antimicrobial agents(e.g., chlorhexidine), antiplaque agents, anti-tartar agents, othermedicaments, flavorants, sweeteners, and the like.

[0020] According to one embodiment, the dental bleaching composition ismade by first forming a flowable liquid or gel composition that is latersubsequently dried to form a substantially solid bleaching layer. Thismay be performed by heating or otherwise causing one or more volatilesolvents to be driven off by evaporation, thus leaving behind asubstantially solid bleaching composition. The drying process may beperformed before or after the bleaching composition is placed intocontact with the barrier layer.

[0021] According to one embodiment, dental bleaching devices can be madeby spreading a flowable dental bleaching composition onto the surface ofa large or continuous polymeric sheet. The polymeric sheet and bleachingcomposition are then heated, such as in a forced air oven, to drive offa substantial portion of the water or other solvent that was used toform the flowable dental bleaching composition in order to yield asubstantially solid layer of bleaching composition. Thereafter,individual tray-like dental bleaching devices can be molded or stampedfrom the large or continuous polymeric sheet coated with thesubstantially solid layer of bleaching composition and then separated asindividual bleaching devices suitable for placement over a person'steeth.

[0022] Alternatively, a flowable or substantially solid dental bleachingcomposition can be molded or shaped into a desired tray-likeconfiguration comprising the bleaching layer. Thereafter, a barrierlayer can be attached or applied to an outer surface of the bleachinglayer. In yet another embodiment, a dental tray can be coated with aflowable dental bleaching composition, such as by painting or spreading,and then heated or allowed to dry at room temperature so that thebleaching composition becomes substantially solid.

[0023] The size and shape of dental bleaching devices according to theinvention can be tailored to more readily fit a person's upper or lowerdental arch. They may also be tailored to fit person's havingdifferently sized or shaped dental arches. The dental bleaching devicesare advantageously designed so as to substantially cover the front andlingual surfaces of the teeth to bleached. Bleaching both surfacesyields more esthetically appealing teeth. Moreover, bleaching both thefront and lingual surfaces helps in bleaching the interproximal spacesbetween adjacent teeth. The dental bleaching devices are advantageouslyflexible and adhesive so as to readily conform to a wide variety ofdifferently-sized teeth and dental arches.

[0024] The dental bleaching devices according to the invention arepreferably in the shape of a dental tray having a front side wall, arear side wall, and a trough between the front and rear side walls.Having the shape of a dental tray facilitates placement of the dentalbleaching device over a person's teeth by minimizing the amount ofmanipulation that is necessary to obtain a good fit between the deviceand the person's teeth. Dental bleaching devices that are in the shapeof a dental tray and that have a substantially solid bleaching layerthat becomes more adhesive when moistened with water or saliva areeasier to install over a person's teeth than flat bleaching strips. Inaddition, the inventive dental bleaching devices are designed to morereliably remain in place over the person's teeth compared toconventional bleaching strips. The result is more effective toothbleaching and better patient compliance.

[0025] According to one embodiment, the dental bleaching device has ahorseshoe shape and a U-shaped trough like a conventional bleachingtray. In another embodiment, the bleaching device has an L-shapedprofile or “trough”. It will be appreciated, however, that dentalbleaching devices according to the invention can have any longitudinalprofile or shape (e.g., they can be straight or have any desired degreeof longitudinal curvature from one end of the device to the other). Thetrough may have any desired cross-sectional shape (e.g., the trough canbe V-shaped, trapezoidal, rectangular, or other geometric shape).

[0026] To facilitate the ability of a dental treatment device to conformto the various shapes and sizes among dental arches, the dentaltreatment device may include mechanical features such as a notch withinthe front side wall, preferably within an edge near the center of thefront side wall, and/or a notch within the rear side wall, preferablywithin an edge near the center of the rear side wall. Notches allow thetray-like bleaching device to more easily conform to differently-sizeddental arches. In this way, the dental bleaching device can be designedso as to be “one-size fits all”.

[0027] The dental bleaching devices according to the invention can bedesigned to be worn for any desired time period. Increasing theconcentration of dental bleaching agent generally reduces the requiredbleaching time. Nevertheless, due to the extremely comfortable fit andreliable adhesion between the inventive dental bleaching devices and theperson's teeth, it is possible to wear such devices for extended periodsof time in order to ensure even and thorough bleaching. Dental bleachingdevices according to the invention can be designed to be worn while,e.g., talking, sleeping, eating, drinking, smiling, frowning, grimacing,yawning, coughing, smoking, or making virtually any facial expression ormouth contortion. This greatly decreases their intrusiveness intoeveryday activities compared to conventional bleaching strips, which donot reliably adhere to teeth, or intrusive bleaching devices such aslarge, bulky bleaching dental appliances.

[0028] The dental bleaching devices can be designed to be worn for aslittle as a few minutes or as long as several hours. By way of example,not limitation, a typical bleaching session of fast duration may lastfrom about 10 to about 30 minutes. A bleaching session of intermediateduration may last from about 30 minutes to about 2 hours. A bleachingsession of long duration, including professional bleaching or overnightbleaching while a person is sleeping, may last from about 2 hours toabout 12 hours. Bleaching sessions may be repeated as many times as areneeded to obtain a desired degree of whitening. In some cases, aclinical whitening effect has been observed after only 1-3 whiteningsessions. A typical bleaching regimen will preferably include 1-20bleaching sessions, more preferably 2-15 bleaching sessions, and mostpreferably 3-10 bleaching sessions.

[0029] For convenience of use, multiple dental bleaching devices may bepackaged together and sold as a kit. In one embodiment, the number ofdental bleaching devices provided with each kit can equal the number ofsessions that represent a prescribed bleaching regimen. To efficientlyutilize the space within a kit package, multiple dental bleachingdevices can be stacked and interested together. The dental bleachingdevices can be sealed collectively or individually as desired. They maycontain a removable protective layer on their interior surfaces toprotect the bleaching layer from contamination or moisture, both ofwhich can possibly cause premature decomposition of the peroxidebleaching agent. It is within the scope of the invention to providebarrier layers and bleaching composition that are initially separate andthat are brought together by the end user. The bleaching composition maybe a dry or substantially solid insert or it may be a liquid or gel thatis applied to the barrier and allowed to dry prior to placement of thefinished dental treatment device over the person's teeth.

[0030] These and other advantages and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To further clarify the above and other advantages and features ofthe present invention, a more particular description of the inventionwill be rendered by references to specific embodiments thereof, whichare illustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

[0032]FIG. 1 is a perspective view of an exemplary dental bleachingdevice according to the invention in the shape of a dental traycomprising a barrier layer and a substantially solid dental bleachingcomposition;

[0033]FIG. 2 is a cross-sectional view of the dental bleaching devicedepicted in FIG. 1;

[0034]FIG. 3 illustrates the dental bleaching device of FIG. 1 containedwithin a sealed protective package having a peelable cover;

[0035]FIG. 4 is a perspective view of an exemplary dental bleachingdevice that is similar to the bleaching device depicted in FIG. 1, butthat further includes a terminal side wall on each longitudinal end;

[0036]FIG. 5 is a perspective view of an exemplary dental bleachingdevice having an L-shaped trough and a curved longitudinal profile;

[0037]FIG. 6 is a perspective view of an exemplary dental bleachingdevice having a U-shaped trough and a substantially straightlongitudinal profile;

[0038]FIG. 7 is a perspective view of an exemplary dental bleachingdevice having a V-shaped trough and a curved longitudinal profile;

[0039]FIG. 8 illustrates a person placing a dental bleaching deviceaccording to the invention over the upper dental arch; and

[0040]FIG. 9 illustrates a person placing a dental bleaching deviceaccording to the invention over the lower dental arch, with a dentalbleaching device already placed over the upper dental arch.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] I. Introduction and Definitions

[0042] The present invention generally relates to improved dentalbleaching devices used to bleach a person's teeth. The inventive dentalbleaching devices include a moisture-resistant barrier layer and asubstantially solid dental bleaching composition that becomes moreadhesive to teeth when moistened with water or saliva. When placed overa person's teeth, the dental bleaching composition reliably adheres tothe teeth, maintaining contact between the teeth to be bleached and ableaching agent within the bleaching composition. The barrier layerprotects the dental bleaching composition from diffusing away from theperson's teeth as a result of ambient saliva or moisture found withinthe person's mouth.

[0043] The inventive bleaching devices are more adhesive to teeth thanconventional bleaching strips. The inventive dental bleaching devicesare also less intrusive than bulky, over-the-counter, non-custom or boiland bite dental trays. In some ways they are as reliable, or even morereliable than custom-fitted dental trays in maintaining the dentalbleaching composition against a person's teeth. In some cases, they arealso as comfortable, or even more comfortable, than custom-fitted trays.

[0044] The term “barrier layer”, as used herein, refers to one or morelayers of a moisture-resistant material that protects the bleachinglayer from ambient moisture and saliva found within a person's mouthwhen the dental bleaching device is placed over the person's teeth. Thebarrier layer may also serve to protect the bleaching layer frommoisture or other contaminants during storage and prior to use. Thebarrier layer may be in any desired form including, but not limited to,a sheet laminated to a surface of the bleaching layer, a coating appliedto a pre-formed bleaching layer, or a dental treatment tray.

[0045] The term “bleaching layer”, as used herein, refers to one or morelayers of a dental bleaching composition that has been formulated orprocessed so as to be substantially solid, coherent, and non-flowable.The bleaching layer may comprise a single continuous region or layeradjacent to the barrier layer, or it may comprise a plurality ofdiscontinuous regions or layers spaced-apart by random or predeterminedintervals.

[0046] The term “substantially solid”, as used herein, refers to adental bleaching composition or bleaching layer that is in a solid orsemi-solid condition. In one aspect, a “substantially solid” bleachingcomposition or layer can be characterized as a continuous or cohesivemass that does not readily flow or separate when subjected togravitational forces and which cannot be readily expressed through asyringe outlet or other similarly-sized opening or orifice. Thus, theterm “substantially solid” excludes runny bleaching liquids, viscousbleaching liquids, and even thick bleaching gels that are able to flowwhen subjected to gravity and/or which can be readily expressed througha syringe outlet or other similarly-sized opening or orifice. The term“substantially solid”, when used in the context of a bleachingcomposition or layer, also excludes dry particulate bleachingcompositions or powders because dry particulates and powders readilyflow when subjected to gravity and/or are readily separated (i.e., theparticles as a whole have little or no internal cohesion).

[0047] One characteristic of “substantially solid” bleachingcompositions or layers according to the invention is that they becomemore adhesive when an exposed surface thereof is moistened with, e.g.,saliva or water. When moistened, the surface of the bleachingcomposition or layer turns into a sticky material that is able to morestrongly adhere to teeth compared to a substantially solid bleachingcomposition or layer that has not been moistened. The composition at thesurface may become a viscous liquid, paste or gel, at least temporarily,depending on the amount of moisture that is applied to the surface ofthe “substantially solid” bleaching composition or layer. Nevertheless,the consistency of the moistened surface can remain “substantiallysolid” depending on the degree of initial moistening, or it can stiffenand even revert back to being “substantially solid” as the initialquantity of surface moisture diffuses into a remaining portion of the“substantially solid” bleaching composition or layer over time (e.g.,during a bleaching procedure in which the bleaching layer or compositionis protected from saliva and ambient moisture in a person's mouth by awater-proof barrier layer).

[0048] The term “dental tray”, as used herein, refers to any article ofmanufacture or device having a tray-like shape so as to facilitateplacement of the device over at least a portion of a person's dentalarch. A “dental tray” or “tray-like” device includes a front side wallconfigured to engage front surfaces of a person's teeth when in use, arear side wall extending laterally from the front side wall, eitherabruptly by one or more distinct angles or non-abruptly by a curvedtransition, configured to engage lingual surfaces of the person's teeth,and a trough between said front and rear side walls. A “dental tray” maybe configured so that a portion of the front side wall, rear side wall,or a transition portion thereof engages the incisal or occlusal edges ofthe person's teeth when in use. The dental tray may be curved orstraight in a longitudinal dimension.

[0049] The term “trough”, as used herein, refers to the region that isat least partially bounded by the front side wall, the rear side wall,and a plane or imaginary curved dome extending from an upper edge of thefront side wall and an upper edge of the rear side wall. Thus, a“trough” can theoretically exist whenever the front and rear side wallshave a space therebetween and are laterally offset by an angle of lessthan 180°. In practice, the front and rear side walls will be offset byan angle that is preferably less than about 150°, more preferably lessthan about 120°, and most preferably less than about 90°.

[0050] In the case of a trough having a U-shaped or rectangular crosssection, at least a portion of the front and rear side walls may besubstantially parallel (i.e., be offset by an angle of approximately0°). In the case of a trough having a V-shaped or trapezoidal crosssection, at least a portion of the front and rear side walls may beoffset by an acute angle (i.e., by an angle between 0-90°). In the caseof a trough having an L-shaped cross section, at least a portion of thefront and rear side walls will be offset by an angle centered aroundapproximately 90° (e.g., by an angle in a range of about 70° to about110°). Thus, a trough having an L-shaped cross section can be a subsetor slight variation of a trough having a V-shaped cross section.

[0051] The terms “longitudinal”, “longitudinal dimension” and“longitudinal profile”, as used herein when used to refer to a dentaltray or dental treatment device, shall refer to the lengthwise dimensionof the tray or device. The tray or device may be straight in the“longitudinal dimension” or it may be horseshoe-shaped or otherwise“longitudinally curved” in the longitudinal dimension so as toapproximate the curvature of a person's dental arch, or at leastfacilitate placement of the tray or device over the dental arch.

[0052] The term “molecular weight”, as used herein, refers to numberaverage molecular expressed in Daltons unless otherwise specified.

[0053] II. Dental Bleaching Devices

[0054] Inventive dental bleaching devices according to the inventioninclude a bleaching layer that becomes more adhesive to teeth whenmoistened by, e.g., saliva or water, and a moisture-resistant barrierlayer that protects the bleaching layer from ambient moisture within aperson's mouth during use. Following are preferred examples of materialsand characteristics of barrier layers and bleaching layers according tothe invention.

[0055] A. Barrier Layers

[0056] According to one embodiment of the invention, the barrier layercomprises a thin, flexible membrane formed from a moisture-resistantpolymer material. In a preferred embodiment, the barrier layer comprisesa thin, flexible layer of a polyolefin or similarly moisture-resistantmaterial, such as wax, metal foil, paraffin, ethylene-vinyl acetatecopolymer (EVA), ethylene-vinyl alcohol copolymer (EVAL),polycaprolactone (PCL), polyvinyl chloride (PVC), polyesters,polycarbonates, polyamides, polyurethanes or polyesteramides. Suchmaterials may be provides in the form of large, flat, flexible sheets towhich the bleaching layer is applied. Alternatively, such sheets may beapplied or attached to an existing bleaching layer comprising asubstantially solid dental bleaching composition.

[0057] Notwithstanding the foregoing, it is within the scope of theinvention to provide barrier layers having any desired material,thickness or rigidity so long as the barrier layer provides at leastsome moisture protection relative to the bleaching layer. The barrierlayer may comprise a conventional dental tray, examples of which includeboth customized and non-custom dental trays. The barrier layer may be assimple as a layer of a moisture resistant material that is sprayed orpainted on, applied by dipping, or otherwise applied to an existingbleaching layer (e.g., one that is in the form of a dental tray or thatotherwise has a desired shape).

[0058] Examples of suitable polyolefins for use in making the barrierlayer include, but are not limited to, polyethylene (PE), high densitypolyethylene (HDPE), low density polyethylene (LDPE), ultra low densitypolyethylene (ULDPE), polypropylene, and polytetrafluoroethylene (PTFE)(e.g., TEFLON). An example of a suitable polyester for use in making thebarrier layer includes, but is not limited to, polyethyleneterephthalate (PET), an example of which is MYLAR, sold by DuPont.Plasticizers, flow additives, and fillers known in the art can be usedas desired to modify the properties of any of the foregoing polymersused to form the barrier layer.

[0059] As will be discussed below, some dental bleaching compositionswill be more adhesive to polymer materials comprising the barrier layerthan others, often depending on the tooth adhesion agent that is used.It has been found that, as between polyethylene, paraffin andpolyethylene terephthalate, substantially solid dental bleachingcompositions tend to adhere more strongly to polyethylene terephthalate,particularly MYLAR.

[0060] It is also within the scope of the invention to utilize barrierlayers that are formed onto a surface of a previously formed bleachinglayer, such by adhering a sheet or tray-like barrier layer to thebleaching layer. Alternatively, the barrier layer may itself beinitially flowable and later hardened, such as a lacquer that contains abarrier material (e.g., a cellulosic ether, cellulose acetate, wax,plastic, polyvinyl acetate, polyvinyl alcohol, or shellac) dissolved inone or more solvents that are later removed; a chemical or light-curematerial (e.g., a methacrylate or acrylate resin); or a thermoplasticmelt (e.g., any thermoplastic resin). Examples of useful cellulosicethers that can be used to form a barrier layer include, but are notlimited to, ethyl cellulose, propyl cellulose, isopropyl cellulose,butyl cellulose, t-butyl cellulose, and the like.

[0061] B. Bleaching Layers

[0062] Prior to being moistened in preparation for or during use,bleaching layers within dental bleaching devices according to theinvention preferably comprise a substantially solid and coherent dentalbleaching composition, as opposed to a liquid, a flowable gel, or a drypowder or particulate bleaching composition. The bleaching layer maycomprise a single coherent mass or region, or it may comprise aplurality of coherent masses or regions of a substantially solid dentalbleaching composition. Providing a substantially solid and coherentbleaching layer better maintains the bleaching composition between thebarrier layer and the teeth being bleached instead of diffusing into thesurrounding oral cavity, as compared to conventional bleaching gels thatare loaded into customized or non-customized dental trays or that areapplied using bleaching strips. This, in turn, promotes better toothwhitening and reduces irritation to surrounding oral tissues and/or atleast some of the bad taste normally associated with dental bleaching.

[0063] Substantially solid dental bleaching compositions that comprisethe bleaching layer according to the invention include at least onebleaching agent and at least one tooth adhesion agent. In a preferredembodiment, the bleaching agent is dispersed within a substantiallysolid matrix comprising the tooth adhesion agent. Following arepreferred bleaching agents and tooth adhesion agents.

[0064] 1. Bleaching Agents

[0065] A common dental bleaching agent that is known to bleach teeth andthat has been found to be safe for oral use is hydrogen peroxide.However, hydrogen peroxide does not itself exist free in nature, butonly as an aqueous solution or as a complex. Preferred dental bleachingagents comprise complexes of hydrogen peroxide because they are morestable than aqueous hydrogen peroxide, which tends to be unstable whenheated, especially when water is removed by evaporation.

[0066] Non-limiting examples of complexed hydrogen peroxide includecarbamide peroxide and metal perborates. Other bleaching agents that canbe used to bleach teeth include, but are not limited to, metalpercarbonates, peroxides, chlorites, and hypochlorites, peroxy acids,and peroxy acid salts.

[0067] Bleaching agents within the substantially solid dental bleachingcompositions according to the invention can have any desiredconcentration, e.g., between 1-90% by weight of the substantially soliddental bleaching composition. The concentration of the dental bleachingagent can be adjusted depending on the intended treatment time for eachbleaching session. In general, the shorter the treatment time, the morebleaching agent will be added to accelerate dental bleaching so as toeffect bleaching in a shorter time period.

[0068] The one or more bleaching agents are preferably included in anamount in a range of about 5% to about 80% by weight of thesubstantially solid dental bleaching composition, more preferably in arange of about 10% to about 60% by weight of the substantially soliddental bleaching composition, and most preferably in a range of about20% to about 50% by weight of the substantially solid dental bleachingcomposition.

[0069] 2. Tooth Adhesion Agents

[0070] The tooth adhesion agent may comprise any known tackifying agentthat is substantially non-adhesive, or less adhesive, when the dentalbleaching composition is substantially solid but which becomes moreadhesive to teeth when the dental bleaching composition is moistenedwith, e.g., water or saliva. A presently preferred tooth adhesion agentis polyvinyl pyrrolidone (PVP). PVP polymers have been found to provideexcellent adhesion to polymer barrier layers made from PE, PET andparaffin, to be substantially non-adhesive adhesive when the dentalbleaching composition is dry to the touch, and to have superior adhesionto teeth when a surface of a substantially solid dental bleachingcomposition is moistened with saliva or water.

[0071] Non-limiting examples of polyvinyl pyrrolidone polymers that havebeen used in formulating bleaching compositions and layers according tothe invention include Kollidon 30, a polyvinyl pyrrolidone polymer soldby BASF having a molecular weight of 50,000, Kollidon VA 60, a polyvinylpyrrolidone polymer having a molecular weight of 60,000, and Kollidon 90F, a polyvinyl pyrrolidone polymer having a molecular weight of 1.3million. Because PVP polymers having widely varying molecular weightshave been found to provide similar adhesion and wetting properties, itis believed that PVP polymers of any molecular weight, at least thosehaving a molecular weight between 50,000 and 1.3 million, will be usefulin formulating substantially solid bleaching compositions or layersaccording to the invention.

[0072] Other tooth adhesion agents that may be used in addition to, orinstead of, PVP within the scope of the invention include, but are notlimited to, carboxypolymethylene (e.g., CARBOPOL, sold by Novean, Inc.),polyethylene oxide (e.g., POLYOX, made by Union Carbide), polyacrylicacid polymers or copolymers (e.g., PEMULEN, sold by Novean, Inc.),polyacrylates, polyacrylamides, copolymers of polyacrylic acid andpolyacrylamide, PVP-vinyl acetate copolymers, carboxymethylcellulose,carboxypropylcellulose, polysaccharide gums, proteins, and the like.

[0073] Although polyethylene oxide polymers comprises a less preferredtooth adhesion agent, it has been found that a polyethylene oxidepolymer having a molecular weight of 1 million provides better adhesionto barrier layers such as MYLAR than a polyethylene oxide polymer havinga molecular weight of 100,000.

[0074] The one or more tooth adhesion agents are preferably included inan amount in a range of about 10% to about 90% by weight of thesubstantially solid dental bleaching composition (exclusive of any boundwater or other solvent), more preferably in a range of about 20% toabout 80% by weight of the substantially solid dental bleachingcomposition, and most preferably in a range of about 40% to about 75% byweight of the substantially solid dental bleaching composition.

[0075] 3. Other Components

[0076] The dental bleaching composition may include other components asdesired to yield a final composition having desired properties. Examplesof other components include, but are not limited to, plasticizers andhumectants (e.g., glycerin, sorbitol, and polyethylene glycol), volatilesolvents (e.g., water and alcohols, such as ethanol), stabilizing agents(e.g., EDTA), neutralizing agents (e.g., sodium hydroxide), thickeningagents (e.g., fumed silica), desensitizing agents (e.g., potassiumnitrate, other potassium salts, citric acid, citrates, and sodiumfluoride), remineralizing agents (e.g., sodium fluoride, stannousfluoride, sodium monofluorophosphate, and other fluoride salts),antimicrobial agents (e.g., chlorhexidine, troclosan, and tetracycline),antiplaque agents, anti-tartar agents (e.g., pyrophosphates salts),other medicaments, flavorants, sweeteners, and the like.

[0077] When water is used as a solvent when manufacturing bleachinglayers according to the invention and then driven off by evaporation toyield a substantially solid dental bleaching composition, it ispostulated that a significant amount of water remains bound orassociated with the hydrophilic components within the dental bleachingcomposition, including the dental bleaching agent, the tooth adhesionagent, and any polyols added as humectants. Although the amount ofresidual water has not yet been determined, it is believed thatapproximately 10% of the water added initially remains after theinitially flowable dental bleaching composition is dried sufficiently toyield a substantially solid bleaching composition.

[0078] C. Characteristics of Dental Bleaching Devices

[0079] The dental bleaching devices according to the invention arepreferably in the shape of a dental tray having a front side wall, arear side wall, and a trough between the front and rear side walls.Having the shape of a dental tray facilitates placement of the dentalbleaching device over a person's teeth by reducing the amount ofmanipulation that is necessary to obtain a good fit between the deviceand the person's teeth.

[0080] Dental bleaching devices that are in the shape of a dental trayand that have a substantially solid bleaching layer that becomes moreadhesive when moistened with water or saliva are easier to install overa person's teeth compared bleaching strips or patches, which areinitially flat and which must be manipulated so as to wrap the initiallyflat strip or patch around the occlusal or incisal edges of the teeth inorder to cover the front and lingual tooth surfaces. In addition, theinventive dental bleaching devices are designed to more reliably adhereand remain in place over the person's teeth compared to conventionalbleaching strips, which employ a dental bleaching gel that is alreadyflowable prior to placing the bleaching strip over a person's teeth tobe bleached. The result is more effective tooth bleaching and betterpatient compliance. In contrast to conventional bleaching strips, whichare not recommended for use while a person eats, drinks, smokes orsleeps, dental bleaching devices according to the invention can bedesigned so as to be worn while talking, sleeping, eating, drinking,smiling, frowning, grimacing, yawning, coughing, smoking, or makingvirtually any facial expression or mouth contortion.

[0081] According to one currently preferred embodiment, the dentalbleaching device has a horseshoe shaped longitudinal profile and has atrough with a U-shaped cross section, much like a conventional bleachingtray. Such a device is depicted in FIGS. 1 and 2. FIG. 1 is aperspective view of a dental bleaching device 10 having a front sidewall 12 and a rear side wall 14 that together have a generally horseshoeshape in a longitudinal dimension and that define a trough 16 having agenerally U-shaped cross section. The U-shaped cross section of thetrough is seen even more clearly in FIG. 2.

[0082] The dental bleaching device 10 further includes a barrier layer18, preferably comprising a moisture-resistant material, and a coherentbleaching layer 20, preferably comprising a substantially solid dentalbleaching composition. As best seen in FIG. 2, the bleaching layer 20includes an exterior surface 22 disposed adjacent to an interior surface24 of the barrier layer 18 and an interior bleaching surface 26 designedto directly contact a person's teeth when the dental bleaching device 10is in use.

[0083] In order to protect a dental bleaching device according to theinvention from contaminants during storage and prior to use, the dentalbleaching device can be packaged within a sealed container or package.As illustrated in FIG. 3, the dental bleaching device 10 can be sealedwithin a protective package 30 that includes a rigid support layer 32and a peelable cover 34. When it is desired to use the dental bleachingdevice 10, the peelable cover 34 is removed and the bleaching device 10is removed or separated from the support layer 32. In addition to, orinstead of, the protective package 30, the dental bleaching device 10may alternatively include a removable protective layer (not shown) thatis temporarily placed adjacent to the interior bleaching surface 26 ofthe bleaching layer 20. When it is desired to use the dental bleachingdevice 10, the removable protective layer is removed so as to expose theinterior bleaching surface 26.

[0084]FIG. 4 illustrates a dental bleaching device 40 that is avariation of the U-shaped dental bleaching device 10 of FIG. 1. The maindifference is that each longitudinal end 42 of the dental bleachingdevice 40 is raised so as to at least partially enclose the last toothon each side of a person's dental arch when the bleaching device 40 isin use.

[0085]FIG. 5 illustrates an alternative embodiment of a dental bleachingdevice 50 according to the invention that is L-shaped. Moreparticularly, the dental bleaching device 50 includes a front side wall52 and a rear side wall 54 extending laterally from the front side wall52 so as to form a trough 56 having an approximate L-shaped crosssection. The L-shaped bleaching device 50 of FIG. 4 is somewhat easierto initially place over a person's dental arch compared to the U-shapedbleaching devices of FIGS. 1-4. This is due to the approximately planarorientation of the rear side wall 54 relative to the occlusal or incisaledges of a person's teeth when the front side wall 52 of the dentalbleaching device 50 is initially placed and adhered against the frontsurfaces of a person's teeth. On the other hand, more manipulation of anL-shaped device is generally required to form and adhere the rear sidewall 54 against the lingual surfaces of the person's teeth as a resultof the greater initial offset angle between the front side wall 52 andrear side wall 54. However, the ability of dental bleaching devicesaccording to the invention to adhere to tooth surfaces almostimmediately, or within a few seconds, after the substantially solidbleaching composition is wetted facilitates the process of conformingthe front side wall 52 and rear side wall 54 to the person's toothsurfaces.

[0086] In the case of the dental bleaching device 50 having an L-shapedcross section, it may be more correct to say that the rear side wall 54extending laterally from the front side wall 52 is really a bottom wallrather than a rear side wall. Nevertheless, because this erstwhile“bottom wall” of an L-shaped bleaching device is folded back against thelingual tooth surfaces during use, it can be readily seen that ableaching device having an L-shaped trough is merely a variation of adevice having a V-shaped trough. Thus, for purposes of this disclosureand the appended claims, the side wall 54 shall constitute, and fallwithin the definition of, a “rear side wall”.

[0087] To facilitate the ability of a dental treatment device to conformto the varying shapes and sizes among dental arches, the dentaltreatment device may include mechanical features such as one or morenotches within the front or rear side walls. As shown in FIG. 5, thedental bleaching tray 50 includes a notch 58 in an outer edge near thecenter of the front side wall 52 and a notch 59 in an outer edge nearthe center of the rear side wall 54. Notches 58 and 59 allow thetray-like bleaching device to more easily spread open or compress whenbeing conformed to differently-sized dental arches. In this way, thedental bleaching device 50 can more easily be a “one-size fits all”device.

[0088]FIG. 6 depicts an alternative embodiment of a dental bleachingdevice 60 according to the invention, which includes a front side wall62 and a rear side wall 64 that define a U-shaped trough 66. Instead ofbeing horseshoe shaped like the dental bleaching device 10 of FIGS. 1-5,or otherwise having a curved longitudinal profile, the dental bleachingdevice 60 of FIG. 6 has a substantially straight or linear longitudinalprofile.

[0089]FIG. 7 depicts yet another alternative embodiment of a dentalbleaching device 70 according to the invention. The dental bleachingdevice 70 includes a front side wall 72 and a rear side wall 74 thatdefine a V-shaped trough 76 and a curved longitudinal profile. The maindifference between the V-shaped bleaching device 70 of FIG. 7 and theL-shaped bleaching device 50 of FIG. 5 is the angle at which the frontand rear side walls are laterally offset from each other.

[0090] Notwithstanding the foregoing examples, it will be appreciatedthat dental bleaching devices according to the invention can have anylongitudinal shape (e.g., they can have a straight or curvedlongitudinal profile from one end to the other). The front and rear sidewalls may define a trough of any desired cross-sectional shape (e.g.,the trough can be trapezoidal, rectangular, or any other desiredgeometric shape).

[0091] The size and shape of dental bleaching devices according to theinvention can be tailored to more readily fit either a person's upperdental arch or lower dental arch. They an be sized so as to bleach allor merely a subset of a person's teeth. The dental bleaching devices maybe sufficiently adhesive and flexible so as to readily conform to a widevariety of differently-sized teeth and dental arches. The dentalbleaching devices are advantageously designed so as to substantiallycover the front and lingual surfaces of the teeth to bleached. Bleachingboth surfaces yields more esthetically appealing teeth, although it iscertainly within the scope of the invention to bleach more of onesurface than another. Bleaching the front and lingual surfaces helps tobleach the interproximal spaces between adjacent teeth.

[0092] In general, the thickness of the barrier layer and/or thebleaching layer can be adjusted to yield a dental bleaching devicehaving a desired strength and flexibility. In order for the barrierlayer to remain flexible so as to conform to a person's teeth, thebarrier layer will generally have a thickness ranging from about 0.025mm to about 1.5 mm. The bleaching layer will generally have a thicknessranging from about 0.1 mm to about 3 mm. The thickness of the bleachinglayer can also be selected depending on the intended duration of eachbleaching session. In generally, increasing the thickness of thebleaching layer will provide a longer or more sustained release ofactive dental bleaching agent. By way of example, for short wear times,the bleaching layer will preferably have a thickness ranging from about0.1 mm to about 0.5 mm. For intermediate wear times, the bleaching layerwill preferably have a thickness ranging from about 0.5 mm to about 2mm. For professional use and for overnight bleaching, the bleachinglayer will preferably have a thickness ranging from about 2 mm to about3 mm.

[0093] III. Methods of Making Dental Bleaching Devices

[0094] According to one embodiment, the dental bleaching composition ismade by first forming a flowable bleaching composition that is laterdried to form a substantially solid bleaching layer. This may beperformed by heating or otherwise causing one or more volatile solventsto be driven off by evaporation, thus leaving behind a substantiallysolid bleaching composition. The drying process may be performed beforeor after the bleaching composition is placed into contact with thebarrier layer.

[0095] According to one embodiment, dental bleaching devices can be madeby spreading a flowable dental bleaching composition onto the surface ofa large or continuous polymeric sheet. The polymeric sheet and bleachingcomposition are then placed into a forced air oven or other appropriatedesiccation device in order to heat and drive off a substantial portionof the water or other solvent used to form the flowable dental bleachingcomposition. Removal of the volatile solvent yields a bleaching layercomprising a substantially solid bleaching composition. Thereafter,individual tray-like dental bleaching devices can be molded, such as byvacuum forming, pressing or stamping from the coated polymeric sheet andthen separated into individual bleaching devices suitable for placementover a person's teeth.

[0096] Alternatively, a flowable dental bleaching composition or asubstantially solid dental bleaching composition can be molded or shapedinto a desired tray-like configuration comprising the bleaching layer.Thereafter, the barrier layer is attached or applied to an outer surfaceof the bleaching layer. In this embodiment, the barrier layer mayinitially comprise a flowable barrier material or precursor that islater cured or hardened, such as by removing a solvent by evaporation,by chemical or light curing, or by cooling a thermoplastic melt.

[0097] In yet another embodiment of the invention, a barrier layer inthe form of a dental tray or tray-like device (e.g, a customized ornon-custom tray) can be coated with a flowable dental bleachingcomposition. The bleaching composition is then heated together with thedental tray or otherwise allowed to dry in order to form a bleachinglayer comprising a substantially solid bleaching composition. Thisprocess can be performed during commercial manufacture of the bleachingdevice or by an end user.

[0098] IV. Methods of Using Dental Bleaching Devices

[0099] The dental bleaching devices according to the invention can bedesigned to be worn for any desired time period. Increasing theconcentration of dental bleaching agent generally reduces the bleachingtime required to effect bleaching. Nevertheless, due to the extremelycomfortable fit and reliable adhesion between the inventive dentalbleaching devices and the person's teeth, it is possible to wear suchdevices for extended periods of time in order to ensure more uniformbleaching. They may be designed to be worn while performing normal dailyactivities, such as talking, eating, drinking, smoking, coughing,smiling, frowning, grimacing, or while sleeping. This greatly decreasestheir intrusiveness into everyday activities compared to conventionalbleaching strips, which do not reliably adhere to teeth, or intrusivebleaching devices such as large, bulky bleaching dental appliances.

[0100] Dental bleaching devices according to the invention may be wornover a person's upper dental arch, lower dental arch, or bothsimultaneously. The ability to reliably and comfortably wear dentalbleaching devices over the upper and lower dental arches simultaneouslyis another departure from bleaching strips, which are not recommendedfor use in bleaching the upper and lower dental arches at the same time.

[0101]FIG. 8 illustrates a person 80 placing a dental treatment device82 over the person's upper dental arch. FIG. 9 illustrates the person 80placing a dental treatment device 92 over the person's lower dental archafter having placed the dental treatment device 82 over the upper dentalarch. It will be appreciated, however, that the dental treatment devicescan be placed over a person's upper and lower dental arches in anydesired order.

[0102] To remove the bleaching device, a user can pry open a corner ofthe barrier using a fingernail or rigid tool and then pull the remainderoff. Any residual bleaching composition that remains adhered to theperson's teeth can be removed by washing or flushing water over theperson's teeth, and/or by brushing. Although dental bleachingcompositions are very adhesive to teeth when protected from excessivemoisture, they can be formulated to quickly breakdown and dissolve whenflushed with excess water and/or by gentle mechanical action (e.g.,brushing).

[0103] The dental bleaching devices can be worn for as little as a fewminutes and as long as several hours. By way of example, not limitation,a typical bleaching session of fast duration may last from about 10 toabout 30 minutes. A bleaching session of intermediate duration may lastfrom about 30 minutes to about 2 hours. A bleaching session of longduration, including professional bleaching or overnight bleaching whilea person is sleeping, may last from about 2 hours to about 12 hours.

[0104] Bleaching sessions may be repeated as many times as are needed toobtain a desired degree of whitening. In some cases, a clinicalwhitening effect has been observed after only 1-3 whitening sessions. Atypical bleaching regimen will preferably include 1-20 bleachingsessions, more preferably 2-15 bleaching sessions, and most preferably3-10 bleaching sessions.

[0105] V. Dental Bleaching Kits

[0106] For convenience of use, multiple dental bleaching devices may bepackaged together and sold as a kit. In one embodiment, the number ofdental bleaching devices provided with each kit will equal the number ofsessions that represent a prescribed bleaching regimen. Because of theease of placing the inventive dental bleaching devices over a person'steeth, coupled with the reliability with which they achieve adhesion toteeth, the likelihood that a particular bleaching device will not workas intended or fail is greatly decreased compared to conventionalbleaching strips.

[0107] To efficiently utilize the space within a kit package, multipledental bleaching devices can be stacked or interested together. Thedental bleaching devices can be sealed collectively or individually asdesired. A protective package 30 is depicted in FIG. 3. The bleachingdevices may optionally contain a removable protective layer on aninterior surface to protect the bleaching layer from contamination ormoisture.

[0108] It is within the scope of the invention to provide barrier layersand bleaching composition that are initially separate and that arebrought together by the end user. For example, the bleaching layer maybe a dry insert comprising a dental bleaching composition that is placedinto a trough of a tray-like barrier layer, with or without actuallyadhering the bleaching layer to the barrier layer. Alternatively, aflowable dental bleaching composition can be placed within the trough ofa tray-like barrier layer and allowed to dry prior to placement of thefinished dental treatment device over the person's teeth.

VI. EXAMPLES OF THE PREFERRED EMBODIMENTS

[0109] The following are several examples of dental bleaching devicesthat have been formulated and manufactured according to the invention.Such exemplary formulations and manufacturing conditions are given byway of example, and not by limitation, in order to illustrate dentalbleaching devices that have been found to be useful for bleaching aperson's teeth. Unless otherwise indicated, all percentages are byweight.

Example 1

[0110] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 16% Polyvinyl pyrrolidone (M.W. = 1.3million) 38% Water 46%

[0111] The resulting bleaching composition was spread over the surfacesof three types of flexible polymer sheets: polyethylene sheets having athickness of approximately 0.15 to 0.18 mm; sheets made of paraffinhaving a thickness of approximately 0.05 to 0.08 mm; and MYLAR sheetshaving a thickness of approximately 0.38 mm. The bleaching compositionwas spread using a spatula. The coated sheets were heated in a forcedair oven heated to a temperature of 50-70° C. for approximately 1 hour.The coated sheets were removed from the oven and inspected. Thebleaching composition had dried sufficiently so as to form a solid,coherent layer of bleaching layer on the surface of the polymer sheets.The dried bleaching composition adhered well to each of the polymersheets. The coated sheets were placed back into the oven overnight toremove additional water and to determine whether prolonged heating ofthe dried composition would cause the carbamide peroxide bleaching agentto decompose.

[0112] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch.

[0113] The tray-like dental bleaching devices were tested by placingthem over a person's teeth. The residual saliva present on the toothsurfaces moistened the exposed surface of the dry dental bleachingcomposition and caused it to become sticky and very adhesive to teethalmost immediately. The bleaching devices were pressed against theteeth, which caused them to conform to the natural irregularities of thedental arch and adhere firmly against the teeth.

[0114] The tray-like dental bleaching devices were worn for varying timeperiods ranging from several minutes to several hours without becomingdislodged. The formation of oxygen bubbles within the moistenedbleaching composition against the person's teeth indicated that theperoxide bleaching agent remained active and was suitable for bleachingteeth even after the bleaching composition was heated overnight in anoven. In some cases a noticeable bleaching effect was detected afterjust one bleaching session (e.g., a 2-hour bleaching session). In allcases, noticeable bleaching was detected after 1-3 bleaching sessions.

Example 2

[0115] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 16% PolyOx WSR 101 (M.W. = 1 million)  7%Water 77%

[0116] The resulting bleaching gel was spread over the surface of MYLARsheets using a spatula. The coated sheets were heated in a forced airoven heated to a temperature of 50-70° C. for approximately 1 hour. Thecoated sheets were removed from the oven and inspected. The bleachingcomposition had dried sufficiently so as to form a solid, coherent layerof bleaching layer on the surface of the polymer sheets. Unlike thebleaching composition of Example 1, the dried bleaching composition didnot adhere strongly to the polymer sheets but was easily separated fromthe sheets. The coated sheets were placed back into the oven overnight.

[0117] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch.

[0118] The tray-like dental bleaching devices were tested by placingthem over a person's teeth. The residual saliva present on the toothsurfaces moistened the exposed surface of the dry dental bleachingcomposition and caused it to become sticky and adhesive to teeth withina few seconds. The results of Example 2 indicate that, whilepolyethylene oxide was a satisfactory teeth adhesion agent, it was lesssatisfactory in promoting adhesion between a dried dental bleachingcomposition and a polymer sheet.

Example 3

[0119] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 16% Carbopol 974P  5% Aqueous NaOH (50%) 6% Water 73%

[0120] The resulting bleaching gel was spread over the surface of MYLARsheets using a spatula. The coated sheets were heated in a forced airoven heated to a temperature of 50-70° C. for approximately 1 hour. Thecoated sheets were removed from the oven and inspected. Although thebleaching composition dried sufficiently to form a solid, it shrunkconsiderably, probably because of the large amount of water that wasneeded to cause Carbopol to form a gel. Shrinkage of the bleachingcomposition caused the polymer sheet to become partially shriveled up.Whereas shriveling of the polymer sheet was not desired, usingcarboxypolymethylene as a tooth adhesion agent resulted in a driedbleaching composition that adhered to a polymer sheet.

[0121] Thereafter, the coated sheets were removed from the oven afterheating overnight, cut apart into smaller-sized pieces, and shaped intotray-like dental bleaching devices suitable for placement over aperson's teeth. When placed over a person's teeth it took about 5seconds for the dental bleaching composition to become moistened enoughto start becoming sticky and adhesive to teeth. The dental treatmentdevice was able to conform to the person's teeth and remain in placeafter being pressed against the teeth for about 30-60 seconds.

[0122] The results of Example 3 indicate that, while Carbopol 974 P isable to adhere to a MYLAR sheet and appears to be a satisfactory toothadhesion agent once the bleaching composition is sufficiently moistened,it presents a shrinkage problem that can cause undesirable deformationof thin, flexible polymer sheets. One would expect Carbopol 974 P towork better when used with less flexible sheets and/or preformed dentaltrays of sufficient rigidity to avoid shriveling or unwanteddeformation.

Example 4

[0123] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Polyethylene Oxide (M.W. = 100,000)  20% Glycerin 2.5%Sodium Percarbonate 2.4% Water 75.1% 

[0124] The resulting bleaching gel was spread over the surface of MYLARsheets as in Example 2. The coated sheets were heated in a forced airoven heated to a temperature of 50-70° C. for approximately 1 hour. Thecoated sheets were removed from the oven and inspected. The bleachingcomposition had dried sufficiently so as to form a solid, coherent layerof bleaching layer on the surface of the polymer sheets. The bleachingcomposition of Example 4 did not adhere at all to the MYLAR sheets. Thisindicates that the lower molecular weight polyethylene oxide of Example4 was even less adhesive to MYLAR sheets than the higher molecularweight polyethylene oxide of Example 2. Sheets comprising a solid layerof the bleaching composition of Example 2 could also be formed byspreading the composition on a solid surface such as glass, drying thecomposition, and then peeling off the dried composition.

[0125] By comparison, when the bleaching composition of Example 1 wasapplied to a glass surface and then dried, it adhered so strongly thatit could not readily be peeled off the glass surface. Instead, it had tobe forcefully chipped or pried off using a razor blade.

[0126] The dried bleaching composition of Example 4 did, however, adhereto a person's teeth when moistened, although not as well as thebleaching compositions of Examples 1-3. This indicates that thecomposition of Example 4 might have commercial application in atray-like dental bleaching device to the extent that problems adheringto the barrier layer are overcome or are not an issue.

Example 5

[0127] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Water 25% Ethanol 25% Polyvinylpyrrolidone (M.W. = 1.3 million) 38% Glycerin 73%

[0128] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 45 minutes. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. Using a mixture of water andethanol as the solvent allowed the bleaching composition to dry in lessthan time than the compositions of Examples 1-4. The inclusion ofglycerin helped the bleaching composition remain more flexible and lessbrittle after drying. The dried bleaching composition adhered well toeach of the polymer sheets. After initial drying, the coated sheets wereplaced back into the oven overnight.

[0129] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 6

[0130] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Water 21% Ethanol 21% Kollidon VA 64(M.W. = 60,000) 40% Carboxy methyl cellulose  3% PEG 600  5%

[0131] Kollidon VA 64 is a polyvinyl pyrrolidone polymer sold by BASF.The resulting bleaching composition was spread over the surfaces ofpolyethylene, paraffin, and MYLAR sheets as described in Example 1. Thecoated sheets were heated in a forced air oven heated to a temperatureof 50-70° C. for approximately 45 minutes. The coated sheets wereremoved from the oven and inspected. The bleaching composition had driedsufficiently so as to form a solid, coherent layer of bleaching layer onthe surface of the polymer sheets. The inclusion of polyethylene glycolhelped the bleaching composition remain more flexible and less brittleafter drying. The dried bleaching composition adhered well to each ofthe polymer sheets. The coated sheets were placed back into the ovenovernight.

[0132] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 7

[0133] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 11.6% Ethanol 55.8% Kollidon VA 90 F(M.W. = 1.3 million) 24.4% Carboxy methyl cellulose  2.3% PEG 600  5.8%

[0134] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 30 minutes. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. Using ethanol as the onlysolvent allowed the bleaching composition to dry in even less time thanthe compositions of Examples 5 and 6. The dried bleaching compositionadhered well to each of the polymer sheets. The coated sheets wereplaced back into the oven overnight.

[0135] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 8

[0136] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Ethanol 65% Kollidon VA 90 F (M.W. =1.3 million) 20% PEG 600  5%

[0137] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 30 minutes. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0138] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 9

[0139] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Ethanol 64% Kollidon VA 90 F (M.W. =1.3 million) 25% PEG 600  1%

[0140] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 30 minutes. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0141] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 10

[0142] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Ethanol 64% Kollidon VA 90 F (M.W. =1.3 million) 23% PEG 600  1% Aerosil 200  2%

[0143] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.Aerosil 200 was added as a tackifying agent to promote adhesion of thewet bleaching composition to the polymer sheets. The coated sheets wereheated in a forced air oven heated to a temperature of 50-70° C. forapproximately 30 minutes. The coated sheets were removed from the ovenand inspected. The bleaching composition had dried sufficiently so as toform a solid, coherent layer of bleaching layer on the surface of thepolymer sheets. The dried bleaching composition adhered well to each ofthe polymer sheets. The coated sheets were placed back into the ovenovernight.

[0144] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 11

[0145] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Ethanol 66.9%   Kollidon VA 90 F(M.W. = 1.3 million) 20% PEG 600 0.1%  Aerosil 200  3%

[0146] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 30 minutes. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0147] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 12

[0148] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide   10% PolyOx (M.W. = 1 million)  7.5%Water 75.5% Glycerin   5% Aerosil 200   2%

[0149] The resulting bleaching gel was spread over the surface of MYLARsheets as in Example 2. The coated sheets were heated in a forced airoven heated to a temperature of 50-70° C. for approximately 1 hour. Thecoated sheets were removed from the oven and inspected. The bleachingcomposition had dried sufficiently so as to form a solid, coherent layerof bleaching layer on the surface of the polymer sheets. The bleachingcomposition of Example 12 did not adhere well to the MYLAR sheets. Italso shrunk somewhat after extended drying. The dried bleachingcomposition of Example 12 was able to adhere to a person's teeth whenmoistened.

Example 13

[0150] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Kollidon 90 F (M.W. = 1.3 million)10% Kollidon 30 (M.W. = 50,000) 20% Water 53% Glycerin  5% Aerosil 200 2%

[0151] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 1 hour. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0152] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 14

[0153] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Kollidon 90 F (M.W. = 1.3 million)27% Water 50% Glycerin  7% Aerosil 200  6%

[0154] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 1 hour. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0155] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

Example 15

[0156] An initially flowable dental bleaching composition suitable foruse in manufacturing a substantially solid, cohesive, and non-flowabledental bleaching composition was formed by mixing together the followingcomponents: Carbamide Peroxide 10% Kollidon 90 F (M.W. = 1.3 million)28% Water 50% Glycerin  7% Aerosil 200  5%

[0157] The resulting bleaching composition was spread over the surfacesof polyethylene, paraffin, and MYLAR sheets as described in Example 1.The coated sheets were heated in a forced air oven heated to atemperature of 50-70° C. for approximately 1 hour. The coated sheetswere removed from the oven and inspected. The bleaching composition haddried sufficiently so as to form a solid, coherent layer of bleachinglayer on the surface of the polymer sheets. The dried bleachingcomposition adhered well to each of the polymer sheets. The coatedsheets were placed back into the oven overnight.

[0158] The coated sheets were removed from the oven a second time, cutapart into smaller-sized pieces, and shaped into tray-like dentalbleaching devices suitable for placement over a person's teeth. Thetray-like bleaching devices included front and rear side walls thatdefined a trough having an approximate U- or V-shaped cross section andwere curved in the longitudinal dimension to roughly approximate thecurvature of a dental arch. The tray-like dental bleaching devicesadhered almost immediately when placed over a person's teeth and causeda noticeable bleaching effect within 1-3 sessions.

[0159] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A dental bleaching device in the shape of adental tray suitable for placement over a person's teeth in order tocarry out dental bleaching, comprising: a barrier layer comprising amoisture-resistant material in the shape of a dental tray comprising afront side wall, a rear side wall, and a trough between said front andrear side walls; and a bleaching layer within said trough comprising asubstantially solid dental bleaching composition having a first surfaceadjacent to said barrier layer and a second surface that has increasedadhesiveness to teeth when moistened by saliva or water, said dentalbleaching composition comprising: at least one dental bleaching agent;and at least one tooth adhesion agent that at least partiallycontributes to said increased adhesiveness to teeth when said dentalbleaching composition is moistened by saliva or water.
 2. A dentalbleaching device as defined in claim 1, said bleaching layer comprisinga single coherent mass in the shape of a dental tray comprising a frontside wall, a rear side wall, and a trough between said front and rearside walls.
 3. A dental bleaching device as defined in claim 2, saidbleaching layer having a rigidity so as to at least partially contributeto maintaining said dental bleaching device in the shape of a dentaltray prior to placing said bleaching device over a person's teeth.
 4. Adental bleaching device as defined in claim 3, said bleaching layercontributing more to maintaining said dental bleaching device in theshape of a dental tray than said barrier layer prior to use.
 5. A dentalbleaching device as defined in claim 3, said barrier layer beingflexible so that it will readily conform to the shape of a person'steeth when said dental bleaching device is in use.
 6. A dental bleachingdevice as defined in claim 1, said bleaching layer comprising aplurality of spaced-apart coherent masses.
 7. A dental bleaching deviceas defined in claim 1, said barrier layer having a rigidity so as to atleast partially contribute to maintaining said dental bleaching devicein the shape of a dental tray prior to placing said bleaching deviceover a person's teeth.
 8. A dental bleaching device as defined in claim7, said barrier layer contributing more to maintaining said dentalbleaching device in the shape of a dental tray than said bleaching layerprior to and during use.
 9. A dental bleaching device as defined inclaim 1, said barrier layer being initially horseshoe shaped prior touse so that said dental bleaching device at least approximately conformsto a person's dental arch with minimal longitudinal shaping.
 10. Adental bleaching device as defined in claim 1, said barrier layerinitially having a longitudinal curvature that is less than thecurvature of a person's dental arch prior to use so that additionallongitudinal curving of said dental bleaching device is required whensaid dental bleaching device is placed over a person's teeth.
 11. Adental bleaching device as defined in claim 1, said barrier layerinitially having a substantially straight longitudinal profile prior touse so that longitudinal curving of said dental bleaching device isrequired when said dental bleaching device is placed over a person'steeth.
 12. A dental bleaching device as defined in claim 1, at least aportion of said trough having an approximate U-shaped cross section. 13.A dental bleaching device as defined in claim 1, at least a portion ofsaid trough having an approximate V-shaped cross section.
 14. A dentalbleaching device as defined in claim 1, at least a portion of saidtrough having an approximate L-shaped cross section.
 15. A dentalbleaching device as defined in claim 1, at least a portion of saidtrough having approximately a rectangular or trapezoidal cross section.16. A dental bleaching device as defined in claim 1, said barrier layercomprising at least one polyolefin.
 17. A dental bleaching device asdefined in claim 16, said polyolefin comprising at least one ofpolyethylene, high density polyethylene, low density polyethylene,ultra-low density polyethylene, polypropylene, orpolytetrafluoroethylene.
 18. A dental bleaching device as defined inclaim 1, said barrier layer comprising at least one of wax, metal foil,paraffin, ethylene-vinyl acetate copolymer, ethylene-vinyl alcoholcopolymer, polycaprolactone, polyester, polycarbonate, polyurethane,polyamide, or polyesteramide.
 19. A dental bleaching device as definedin claim 1, said dental bleaching agent comprising at least one ofcarbamide peroxide, metal peroxide, percarbonate, perborate, peroxyacid, peroxy acid salt, chlorite, or hypochlorite.
 20. A dentalbleaching device as defined in claim 1, said dental bleaching agenthaving a concentration in a range of about 5% to about 80% by weight ofsaid dental bleaching composition.
 21. A dental bleaching device asdefined in claim 1, said dental bleaching agent having a concentrationin a range of about 10% to about 60% by weight of said dental bleachingcomposition.
 22. A dental bleaching device as defined in claim 1, saiddental bleaching agent having a concentration in a range of about 20% toabout 50% by weight of said dental bleaching composition.
 23. A dentalbleaching device as defined in claim 1, said tooth adhesion agentcomprising polyvinyl pyrrolidone.
 24. A dental bleaching device asdefined in claim 1, said tooth adhesion agent comprising at least one ofcarboxypolymethylene, polyethylene oxide, polyacrylic acid, copolymer ofpolyacrylic acid, polyacrylate, polyacrylamide, copolymer of polyacrylicacid and polyacrylamide, PVP-vinyl acetate copolymer,carboxymethylcellulose, carboxypropylcellulose, polysaccharide gum,protein.
 25. A dental bleaching device as defined in claim 1, said toothadhesion agent having a concentration in a range of about 10% to about90% by weight of said dental bleaching composition.
 26. A dentalbleaching device as defined in claim 1, said tooth adhesion agent havinga concentration in a range of about 20% to about 80% by weight of saiddental bleaching composition.
 27. A dental bleaching device as definedin claim 1, said tooth adhesion agent having a concentration in a rangeof about 40% to about 75% by weight of said dental bleachingcomposition.
 28. A dental bleaching device as defined in claim 1, saiddental bleaching composition further comprising at least onenon-volatile solvent.
 29. A dental bleaching device as defined in claim1, wherein said dental bleaching device is sized and configured so as tofit over at least a portion of a person's upper dental arch.
 30. Adental bleaching device as defined in claim 1, wherein said dentalbleaching device is sized and configured so as to fit over at least aportion of a person's lower dental arch.
 31. A dental bleaching deviceas defined in claim 1, wherein said barrier layer has a cross-sectionalthickness in a range of about 0.025 mm to about 1.5 mm.
 32. A dentalbleaching device as defined in claim 1, wherein said bleaching layer hasa cross-sectional thickness in a range of about 0.1 mm to about 3 mm.33. A dental bleaching device as defined in claim 32, wherein saidbleaching layer has a cross-sectional thickness in a range of about 0.11mm to about 0.5 mm.
 34. A dental bleaching device as defined in claim32, wherein said bleaching layer has a cross-sectional thickness in arange of about 0.5 mm to about 2 mm.
 35. A dental bleaching device asdefined in claim 32, wherein said bleaching layer has a cross-sectionalthickness in a range of about 2 mm to about 3 mm.
 36. A dental bleachingdevice as defined in claim 1, wherein said barrier layer is sized andconfigured so as to approximately terminate at or near a person'sgingival margin when said dental bleaching device is in use.
 37. Adental bleaching device as defined in claim 1, wherein said dentalbleaching device is contained within a sealed package prior to use. 38.A kit for use in bleaching a person's teeth comprising a plurality ofdental bleaching devices according to claim
 1. 39. A kit as defined inclaim 38, wherein at least some of said dental bleaching devices arestacked and interested together.
 40. A kit as defined in claim 38,wherein said kit includes from 3 to 10 dental bleaching devices.
 41. Amethod for bleaching a person's teeth comprising obtaining a dentalbleaching device according to claim 1 and then placing said dentalbleaching device over at least a portion of the person's teeth for adesired time period.
 42. A dental bleaching device in the shape of adental tray suitable for placement over a person's teeth in order tocarry out dental bleaching, comprising: a thin, flexible barrier layercomprising a moisture-resistant material; and a bleaching layer adjacentsaid barrier layer and comprising a substantially solid dental bleachingcomposition in the shape of a dental tray comprising a front side wall,a rear side wall, and a trough between said front and rear side walls,the bleaching layer having a rigidity so that said bleaching layercontributes more to maintaining said dental bleaching device in theshape of a dental tray prior to use than said barrier layer, saidbleaching composition having increased adhesiveness to teeth whenmoistened by saliva or water, said bleaching composition comprising: atleast one dental bleaching agent; and at least one tooth adhesion agentthat at least partially contributes to said increased adhesiveness toteeth when said dental bleaching composition is moistened by saliva orwater.
 43. A dental bleaching device as defined in claim 42, at least aportion of said trough having a cross section that is approximatelyU-shaped, V-shaped, L-shaped, rectangular, or trapezoidal.
 44. A dentalbleaching device in the shape of a dental tray suitable for placementover a person's teeth in order to carry out dental bleaching,comprising: a barrier layer comprising a moisture-resistant material inthe shape of a dental tray comprising a front side wall, a rear sidewall, and a trough between said front and rear side walls; and ableaching layer within said trough comprising a substantially soliddental bleaching composition having a first surface adjacent to at leastone of said front side wall or rear side wall and a second surface thathas increased adhesiveness to teeth when moistened by saliva or water,said dental bleaching composition comprising: at least one dentalbleaching agent; and at least one tooth adhesion agent that at leastpartially contributes to said increased adhesiveness to teeth when saiddental bleaching composition is moistened by saliva or water, saidbarrier layer having a rigidity so that said barrier layer contributesmore to maintaining said dental bleaching device in the shape of adental tray prior to use than said bleaching layer.
 45. A dentalbleaching device as defined in claim 44, at least a portion of saidtrough having a cross section that is approximately U-shaped, V-shaped,L-shaped, rectangular, or trapezoidal.
 46. A method for bleaching aperson's teeth, comprising: (a) obtaining a dental bleaching device inthe shape of a dental tray comprising a front side wall, a rear sidewall, and a trough between said front and rear side walls, the dentalbleaching device further comprising: an outer barrier layer comprising amoisture-resistant material; and a bleaching layer comprising asubstantially solid dental bleaching composition having increasedadhesiveness to teeth when moistened by saliva or water, said dentalbleaching composition comprising: at least one dental bleaching agent;and at least one tooth adhesion agent that at least partiallycontributes to said increased adhesiveness to teeth when said dentalbleaching composition is moistened by saliva or water; (b) moistening anexposed surface of said bleaching layer so as to increase adhesivenessof said bleaching layer to teeth; and (c) placing said dental bleachingdevice over at least a portion of the person's teeth for a desired timeperiod, the moistened bleaching layer adhering and retaining said dentalbleaching device against the person's teeth during the desired timeperiod.
 47. A method for bleaching a person's teeth as defined in claim46, wherein (b) is performed by applying water or an aqueous solution tosaid exposed surface.
 48. A method for bleaching a person's teeth asdefined in claim 46, wherein (b) is performed by allowing residualsaliva on the person's teeth to moisten said exposed surface as thedental bleaching device is placed over the person's teeth.
 49. A methodfor bleaching a person's teeth as defined in claim 46, furthercomprising removing said dental bleaching device and any remainingdental bleaching composition.
 50. A method for bleaching a person'steeth as defined in claim 49, said dental bleaching device being removedabout 10 to about 30 minutes after being placed over the person's teeth.51. A method for bleaching a person's teeth as defined in claim 49, saiddental bleaching device being removed about 30 minutes to about 2 hoursafter being placed over the person's teeth.
 52. A method for bleaching aperson's teeth as defined in claim 49, said dental bleaching devicebeing removed about 2 hours to about 12 hours after being placed overthe person's teeth.
 53. A method for bleaching a person's teeth asdefined in claim 46, at least a portion of said trough of said dentalbleaching device having a cross section that is approximately U-shaped,V-shaped, L-shaped, rectangular, or trapezoidal.